DE602004004515T2 - DEVICE FOR CONTROLLING HYDRAULIC DRIVE UNITS - Google Patents

Abstract

An arrangement for controlling two drive units which interact with one another, one of which includes a hydraulically driven motor ( 2 ). The motor drives a varying load, and one or more valves ( 6, 7 ) control hydraulic fluid flow through the motor during operation and for starting and stopping of the motor. One of the valves is a flow control valve ( 7 ) for flow control of the hydraulic fluid flow through the motor. The second drive unit ( 37 ) performs a working movement which, under the action of hydraulic flow influences the loading of the motor. The flow of the hydraulic fluid to the second drive unit is controlled in a coordinated way with the control of the flow through the motor.

Description

TECHNICAL TERRITORY

The The present invention relates to an arrangement for control of two drive units which cooperate with each other according to the preamble of claim 1.

STATE OF TECHNOLOGY

Certain Applications of hydraulic systems include the control of two drive units, a work unit with separate movements drive. This may include a hydraulic engine that working under a load that changes dramatically over time, so far led to certain problems Has. A major problem is the risk of interference between the function of the two drive units. The sloth in a usual one hydraulic system can also cause the hydraulic fluid flow insufficient to supply the motor. Another critical Situation with the risk of cavitation damage occurs when the Engine is brought to the stop position.

One Computer-controlled system for controlling the feed of a saw unit on the basis of a number of control parameters is WO 01/84910 known.

EPIPHANY THE INVENTION

A Object of the present invention is an arrangement to create in the interference problems in the control of two separate but coordinated working movements of two hydraulic Drive units are avoided.

These The object is achieved by an arrangement according to the present invention achieved, whose characteristics are evident from the claim below 1 result.

DESCRIPTION THE FIGURES

The The invention will now be described with reference to some exemplary embodiments and with reference to the attached Drawings described.

In show this:

1 a hydraulic system showing the arrangement according to the invention in a first embodiment in an accelerating position;

2 a detailed view of the system according to 1 in a stop position;

3 a detailed view of the system according to 2 in a control position;

4 a further developed part of the hydraulic system according to the invention in a control position;

5 a detailed view of the in 4 represented part in the acceleration position and

6 a corresponding detailed view in stop position.

PREFERRED EMBODIMENTS

A hydraulic system in which the arrangement according to the invention can be applied is correspondingly in the example of 1 shown. The system has a hydraulic fluid line 1 for a main flow, which starts from a hydraulic fluid pump (not shown). There is also a hydraulic fluid volume v in which the hydraulic pressure is maintained. The drive medium is a pressurized hydraulic fluid selected to be a first drive unit in the form of a hydraulic motor enclosed in the system 2 can drive, which has a drive shaft 3 which is adapted to drive a particular form of work unit destined to perform a particular task, for example a saw 11 To drive, such as a chainsaw in a harvesting unit 12 for logging or, to put it more precisely, for sawing wood. The saw unit and the hydraulic motor with its drive shaft are exposed to large and rapid load changes, which brings with it the danger of large and rapid changes in speed. Examples of hydraulic motor types used for such applications are axial-axis hydraulic axial piston machines (see, for example, US-A-6 336 391) or alternatively of the in-line type. Other types of hydraulic motors may also be used, for example, geared motors. The hydraulic motor has an inlet side 4 on, where the hydraulic fluid is supplied under pressure and an outlet side 5 , from which the hydraulic fluid after the pressure drop in the engine in the main line 1 continues to flow. The hydraulic system also has a flow control valve 7 with an inlet 8th and an outlet 9 on, as well as a flow 10 in a valve spool caused by the action of an electro-hydraulic actuation valve 6 can be adjusted, which can be adjusted between an open and a closed position, ie between a stop position and a start / work position and though by means of an actuator (not shown) operated by an operator / computer.

In the example shown, the flow control valve according to the invention 7 downstream from the hydraulic motor 2 with its outlet side 5 connected and in addition to the start / stop function has a control function for controlling a constant flow, which is adapted so that when the actuation valve 6 is in its working position and the hydraulic flow flows through the flow control valve, a substantially constant hydraulic flow through the hydraulic motor 2 is maintained, in principle, regardless of load changes of the engine. The flow control valve 7 Conveniently consists of a Zweiwegetyp, ie with the inlet 8th and the outlet 9 , where the flow 10 is formed so that the flow area depends on the prevailing flow. In this example, this is done by sensing the pressure drop over a subsequent cross-sectional change, for example, a constriction 15 , in the main line via a control line 16 and via a control line 22 reaches the upstream of the constriction 15 with the main 1 is connected, so that in this way the flow through the motor by means of the flow control valve in response to the pressure difference across the constriction is controlled. The pressure scan upstream of the restriction is via the actuation valve 6 directed. However, in addition to the downstream location of the constant flow valve, the restriction may alternatively be located at various locations in the system, as shown in FIG 1 shown so also upstream of the engine 2 or between the engine and the valve. Around the engine is a shunt line 24 arranged, which is a check valve 25 configured to reduce the pressure by opening when the pressure on the exhaust side of the engine increases abruptly.

The operation of the so far described part of the hydraulic system, ie for driving and controlling the motor 2 will be referred to below with reference to 1 described. The general operating condition of the invention is that during normal operation the most optimized speed possible of the engine 2 and its drive shaft 3 must be constantly maintained and that as far as possible fast speed changes must be counteracted as much as possible, despite a rapid load drop. An example of such an application is therefore sawing through a tree trunk 23 where there is a danger that what is referred to as "runaway" occurs through the energy stored in the hoses, etc., indicated by the symbol v, which occurs when the tree trunk is sawn and the load This is done by the flow control valve 7 which is dimensioned to respond quickly, with this valve downstream of the engine 2 is arranged, ie on its outlet side 5 , When the actuation valve 6 is in its stop position, then the flow control valve 7 so controlled that it has a control line 17 by the effect of the system pressure, by the control pressure of a second control line 20 and by a valve spring 18 is closed. In the stop position, the pump pressure acts directly on a control side or on the control master 28 of the flow control valve 7 over the control line 20 one, which causes the slider to flow 10 moved into its final position and thereby shuts off the entire main flow. Each sample of the load via the control line 19 simultaneously samples a low value. If the pump pressure should drop then the force keeping the flow control valve closed decreases. On the other hand, at the same time decreases the power to turn the engine. When the actuation valve 6 is brought from the stop position to the starting position, then the flow control valve 7 through the spring 18 opened and kept open because now on the control area by the pressure in the control line 22 is not acted, which is the same in the starting position as in the control line 16 , While working, the flow control valve acts 7 such as a constant flow flow valve, the goal being to control the hydraulic flow of the fluid through the flow control valve and thus through the engine 2 To keep constant, through the valve, which is fully open when the flow is too low, trying to throttle the flow, ie to brake the engine when the flow is too high. If there is a sample of the load, then the pressure in the system is sampled to provide maximum flow. When stopping, the engine is braked on the back by the actuating valve 6 returns to the stop position, the flow control valve 7 then brought into the closed position.

If both a constant flow control and a stop are made, the hydraulic fluid pressure at the engine inlet becomes 4 in accordance with the system of the present invention throughout this time, unlike known solutions where a stop valve and possibly a constant flow valve is provided upstream of the engine, with the risk of the engine running faster than the flow and he works like a cavitation pump.

The hydraulic system also has a second hydraulic drive unit for driving the working unit, which now first with reference to 1 is described. In this example, the unit of work is in the form of a unit mentioned above 12 shown, which consists of a hydraulically driven chainsaw 11 with an endless saw chain 31 that passes through a drive wheel 32 is driven, which is about the axis of rotation 33 turns and through the drive shaft 3 of the hydraulic motor 2 is driven. The saw chain is made by a guide plate 34 supported for performing saw movements when sawing through a tree trunk 23 around the drive axle 33 is rotatable. In the example shown, there is the second drive unit 36 of a feed unit for the guide plate, which is hydraulically driven and a reciprocating hydraulic unit in the form of a piston-cylinder unit 37 , which in the embodiment according to 1 is designed double acting. Their reciprocating linear motion is converted into a rotary motion, ie, the guide plate feed motion about the axis 33 through the outer end of the piston rod 38 that with the guide plate 34 about a joint 39 and a connecting arm 40 is coupled eccentrically. A hydraulic valve 41 with three positions, which is the guide plate feed valve, is provided to control the feeding of the guide plate.

The sawing torque, ie the torque at which the drive shaft 3 of the hydraulic motor, varies depending on how much the feed of the saw guide plate 34 is, ie, we are the force or the torque that is the feed unit 36 on the saw guide plate applies. It is therefore a well-controlled feed for the guide plate required to achieve a sawing process, which is optimized as much as possible, that is achieved by the impact of wood or sawing in the shortest possible time by a well-balanced combination the optimized feed rate with the motor speed of the hydraulic motor 2 , This was done by a joint operation of the flow control valve 7 and the function of advancing the guide plate achieved. In the example shown, this is achieved by the slide of the flow control valve, which also controls the feed of the guide plate. In this way, the feed of the guide plate is controlled by the speed of the motor. As long as the speed has not reached a desired size, it is ensured that the feed is turned off. When the saw is heavily loaded, the speed is reduced, which also reduces the feed, and then the speed is increased. When the saw is lightly loaded, ie when the load on the drive shaft 3 decreases, then the speed of the motor increases, and as a result, the feed force increases, ie, the feed rate of the guide plate increases. The motor speed and thus also the speed of rotation of the saw chain around the guide plate are thus regulated by the advancement of the guide plate or, more precisely, the feed force is increased or decreased.

The actuation valve 41 for the advancement of the guide plate therefore controls the inlet flow to the piston-cylinder unit 37 , or to be more precise, to the cylinder chamber 43 on one side of the piston 42 , via a first hydraulic fluid line 44 , and a discharge flow from the cylinder chamber 46 on the opposite side of the piston via a second hydraulic fluid line 45 , wherein the flow via an actuating valve to a tank 47 is directed. The actuation valve 41 is in 1 shown in the closed position. In this context, the flow control valve 7 placed in the fully open position, ie in the starting position and indeed by the activation of the actuating valve 6 , This leads to an acceleration position for the rotational speed of the saw by the motor 2 ie before the saw in the tree trunk 23 penetrates. In a second position, in the stop position of the saw (see 2 ) became the valve 41 adjusted at the same time, to which the flow control valve 7 was brought into the closed position, in which case the opposite feed takes place, ie an inflow via the line 45 and thus a return movement of the guide plate in the opposite direction of rotation, ie counterclockwise when the saw is stopped and a return movement takes place. In an intermediate position / regulation position, in the example shown, a forward feed forward constant flow control, ie, a feed via a conduit, takes place 44 , then the guide plate is advanced clockwise (see 1 and 3 ). The hydraulic flow for advancing the guide plate can be guided via a reducing valve.

Since both the function of the advance of the guide plate and the function of the constant flow rate of the hydraulic motor 2 It is important that these two functions do not interfere with each other. This risk is eliminated by coordinating control by the same valve spool, or at least by the same valve spool movement that controls these two functions, that of the actuation / regulation of the flow control valve 7 depend as in the embodiments of 1 - 6 will be shown. In the embodiment of the 1 - 3 have the flow control valve 6 and the actuation Valve 41 separate valve housings and, for example, slides which are mechanically connected, in the example given rigidly connected, for example by a rod 48 so that they perform the same movement.

In the embodiment according to the 4 - 6 a common slide is provided for both functions, ie for the flow control for the rotating motor 2 and for the advancement of the guide plate. In this example, the slider is 50 in the flow control valve 7 in the form of a piston formed in a cylinder bore 51 linearly reciprocable, on the one hand under the action of two counteracting control pressures via the control lines 16 . 22 ' from the two sides of the narrowing 15 and on the other hand by the force of the spring 52 , For reasons of simplification, the start / stop change is in 4 not shown. The control pressures arise in the corresponding cylinder chambers 53 . 53 ' on the two sides of the piston / slide 50 and generate a compressive force against the corresponding piston surface 55 . 55 ' , The feather 52 , which is adjustable via the spring preload, provides the additional force required to determine which pressure drop across the throat 15 and thus at which speed of the motor the slider starts to move. Within the valve housing a number of lines for the hydraulic flows are arranged, which are to be regulated by means of the valve. The main flow, ie the flow, the engine 2 drives, and primarily through the flow control valve 7 is to be regulated, enters through the inlet 12 and enters through the outlet 13 out. The flow regulation is achieved by the slide, which in a known manner a main passage in the form of an annular main incision 54 and a throttle edge 56 ' in the bar 56 of the slider 50 having. By an axial displacement of the cuts under the action of the control pressures and the spring 52 becomes the flow area between the inlet 12 and the outlet 13 regulates, which regulates the main flow. As indicated by the dashed lines, the throttle edge 56 ' be formed with creep wells, which are designed so that they affect the control characteristic.

In the example shown, another passage is in the form of an annular cut 57 in the same valve slide 50 provided, as well as two hydraulic flow lines 58 . 59 which are arranged in the valve housing. These two wires and the creep well 57 form part of a hydraulic flow circuit for the advancement of the guide plate, wherein, however, for the sake of simplicity and according to the in the 4 - 6 illustrated example, a single-acting hydraulic cylinder 60 is used, wherein the return movement of the feed of the guide plate by a compression spring 61 is ensured, with a hydraulic flow line is omitted. The administration 59 is therefore a hydraulic flow line 44 with the cylinder chamber 43 on one side of the piston 42 in connection while the second line 58 over a line 62 communicates with a source of pressure for the hydraulic fluid. In addition, the mouths 63 . 64 the lines 58 . 59 in the hole 51 on two sides of a partition 65 whose position is exactly related to the position of the throttling cut 57 is selected. It is emphasized that the flow for advancing the guide plate is considerably smaller than the main flow, for example 10% of the main flow, for which reason the dimensions of the two throttle arrangements are quite different.

By the arrangement according to the invention can be regulated in this way, the feed of the guide plate during a sawing operation, ie, the rotational movement of the saw or, more precisely, the saw guide plate, so that the speed is optimized. The system is continuously controlled, with priority being given to advancing the guide plate. The passages of the slider 50 ie the passage 54 for the main flow to the engine 2 and the passage 57 for the flow intended for the feed, must be arranged such that in the acceleration position according to 5 , ie with a fully opened main flow, the flow for the feed is closed.

In the flow control spool, a delta pressure is present over the entire flow area, and when the pressure has overcome the bias of the spring, the spool begins to move (see 5 ) It is therefore possible to apply a slider movement to regulate the load before the throttle rim 56 ' begins to complete the mainstream.

When the engine is stopped, then the slider 50 pressed to the left, then the main flow is stopped. Because the slider with drainage holes 66 are provided, these come into contact with the cylinder for advancing the guide plate, which is why this under the action of the return spring 61 returns to its original position.

By an additional passage in the form of a depression or the like in the slide, therefore, an additional passage is obtained with an opening area which changes the flow / speed. This passage can then be used to throttle the flow, for example, to a feed cylinder for the guide plate. In this way, the feed force of the guide plate is controlled to keep the speed of the motor at an operating point that is slightly less than the maximum set speed. If the pressure on the cylinder can not be maintained despite the load-regulating range on the fully open slider (which occurs, for example, when the saw leaves the log), the load on the engine drops, meaning that the speed increases; In this context, the slide continues to move, so that the slide throttles the engine outlet and thus the speed is limited by the constant flow regulation. By adjusting the spring preload, both the operating point and the point for maximum flow are adjusted. In other words, they follow each other, which simplifies the adjustment of the system.

One Another advantage of an integrated load regulation with a constant flow is indeed an economic one. It is considerable less components required, giving money, weight and space saves.

The The invention is not limited to those shown and described above embodiments limited. For example, the saw of a different kind, for example, a circular saw, a band saw or a saw with a straight leaf. The load can be of a completely different Be kind, for example from a drilling device or rolls, which rotate and their speed by another feed movement being affected.

To the Operation of the two functions of flow control and feed motion together and around the two interacting drive units it's for the start / stop function and for the regulation of a constant flow does not require that these are integrated in one and the same valve arrangement. The Regulation of a constant flow means that the goal is to have a constant flow achieve, but that the current flow can vary. Basically can the flow dependent on be controlled by conditions governing the regulation of a constant flow differ. Logging means both logging and within the Wood and paper industry logs on length to cut. Sawing of dressed wood, such as beams is also a possible Application. In principle, all types of material processing are conceivable Area.

Claims (10)

Arrangement for controlling two drive units which interact with each other, one of which consists of a hydraulically driven motor ( 2 ), which is part of a hydraulic system in which a pressurized hydraulic fluid is a main flow through a main line ( 1 ), in which the engine is switched on, wherein the engine is designed such that it is adapted to the drive of a varying load and wherein one or more valves ( 6 . 7 ) are adapted to control the hydraulic flow through the engine on the one hand during operation and on the other hand to start and stop the engine, wherein one of the valves from a flow control valve ( 7 ), which is adapted to the flow control of the hydraulic flow through the engine and wherein the second drive unit ( 37 / 60 ) is adapted to carry out a working movement which, under the effect of the pressurized hydraulic flow, affects the engine load, characterized by means for coordinated control of the flow of hydraulic fluid to / from the second drive unit with control of the flow through the engine. Arrangement according to claim 1, characterized in that the flow control from a constant flow control of the engine ( 2 ), which has an output shaft ( 3 ) for driving under a changing torque load. Arrangement according to claim 2, wherein the two drive units ( 2 . 37 / 60 ) are designed to be a work unit ( 12 ), wherein the second drive unit consists of a hydraulic piston-cylinder unit ( 37 / 60 ), characterized in that the hydraulic fluid flow for driving the piston-cylinder unit ( 37 / 60 ) in a mechanically coordinated manner with the control of the main flow through the engine ( 2 ) is controlled. Arrangement according to claim 3, characterized in that the flow valve ( 7 ) on the one hand leads for the inlet and outlet ( 12 . 13 ) of the main flow through the engine ( 2 ) and on the other hand at least one separate line ( 58 . 59 ) for the flow to / from the piston-cylinder unit ( 37 / 60 ), and in that the flow control valve comprises one or more movable valve bodies ( 50 . 51 ) which is / are designed to deliver both the main flow and the flow to / from the piston-cylinder unit (FIG. 37 / 60 ) can control in a coordinated manner by a valve movement / can. Arrangement according to claim 4, wherein the flow valve ( 7 ) from a slide valve ( 5 ) with a piston valve ( 5 ) which is linearly movable back and forth under the action of a control pressure and which is provided with a passage ( 54 ) for controlling the main flow through a fixed inlet ( 12 ) and an outlet ( 13 ) in a cylindrical bore ( 51 ) is provided in the valve, characterized in that the spool ( 50 ) at least one further passage ( 57 ) for regulating the flow to drive the piston-cylinder unit and also solid lines ( 58 . 59 ) in the cylindrical bore ( 51 ) are arranged. Arrangement according to claim 3, characterized in that the piston-cylinder unit ( 37 ) is double acting. Arrangement according to claim 3, characterized in that the piston-cylinder unit ( 60 ) is single acting. Arrangement according to claim 3, wherein the working unit ( 12 ) from a saw unit with a saw chain ( 31 ) configured to loop in closed loop around a saw guide plate (10). 34 ), which is movable in a feed movement for felling, characterized in that the engine ( 2 ) is designed so that it the saw chain ( 31 ) and that the piston-cylinder unit ( 37 / 60 ) is designed so that it can drive the advancing movement of the saw guide plate. Arrangement according to claim 8, characterized that the feed movement is a rotary movement. Arrangement according to claim 2, characterized in that the flow control valve ( 7 ) is designed so that it both the start / stop and a constant flow control of the engine ( 2 ).